Our Water and Climate Change

By Dr. Herath Manthrithilake

Head, Sri Lanka Programme, IWMI HQ

Not so long ago, the Ceylon Electricity Board (CEB) and the authorities rang the alarm bells about power cuts due to not having any rains in catchment areas. Just a few months ago, and last year as well, we had unprecedented devastating floods. What is really happening?

Based on historical data, experts say rainfall over the Dry Zone of Sri Lanka is reducing and over some parts of Wet Zone it is increasing. The highest decrease of rainfall is observed in the Mahaweli catchment areas. At the same time, we are witnessing a very high amount of rainfall over a short period, i.e., the intensity of rainfall is increasing, causing floods, after which there is no rain for longer periods, causing droughts. Similarly, it is noticeable that the longer-term average day and night time temperatures are increasing and the gap between them is reducing. They say the sea around us too, would gradually rise above the current level. These are now accepted as the impacts of climate change.

Whatever said and done, the predictions seem to be correct: the frequency and the severity of occurrence of these extreme events are increasing. In many areas, water-related extreme events have already become more frequent and/or more severe, and projections indicate a further increase of frequency and severity. If  this is the case, the crucial question is, “are we factoring these valuable observations into our plans and programmes?”  

Studies, which spell out accurate future climate scenarios for Sri Lanka are scarce and even the ones that do exist appear to have contradictory projections, especially with respect to future rainfall. Therefore, accurate quantification of climate change impacts is difficult. The identification of suitable adaptation strategies depends on the quantified impacts.

These impacts trigger a wide variety of secondary effects on water resources, agriculture, livelihoods, health and well-being, and the economy and nature as a whole.

Whether these are due to climate change or not, we may not be able to stop them occurring continuously. If we can’t stop them, we need to adapt and live with them.  We may be able to mitigate some impacts by adopting certain measures.

In my view, we have two options: first and foremost we need to improve the current management practices. We may not be able to and should not manage our water and related infrastructure the way we have done for the last 100 years. We need to manage things differently and we should begin now, especially by introducing better practices than what we have now, before starting special or extraordinary measures.

After the floods, authorities were concerned about reservoir and spillway capacities to accommodate such a high influx of water. However, we should not forget that existing reservoirs seldom get filled and therefore, encroachments are not only along the spill traces but also in and around reservoirs. This brings to mind the hard fact that water management can no longer be passive or reactive. It should be active and strategic.

The problem scientists and engineers face is that the current practices of estimation based on historical data may not be valid under the new conditions. They need to develop new methodologies to estimate suitable measures. We may have to build new reservoirs, look at spillways and discharge traces, and redesign bridges, culverts and pipes increasing their capacities to pass excess water. We need to deal with encroachments and protect the lands in and around water bodies and along natural streams, allowing them to transmit large quantities of spill water without damage to life and property.

In order to avoid disasters and wasteful expenditure, we should adopt “no regrets” options available to us and “climate proof” all new and old infrastructures, similar to Environment Impact Assessment (EIA).

One of the ‘no regret’ adaptation measures recommended is to increase water storage across a continuum: from increasing soil moisture, recharging groundwater, wetlands, to surface storage (from minor to larger reservoirs) where possible. This recommendation is important for Sri Lanka because we are solely dependent on rainwater. Although we repeat his sayings many a times and are proud of King Parakramabahu’s water management policy, we still use only about 4 - 5 % of our rains tapping from surface and groundwater sources and more than 30% still flows to the sea without serving mankind. At the same time, we need to be mindful that many of our existing reservoirs are not getting filled for many years and they get emptied very quickly. This could be due to design data errors or poor water management, or both.

We should cherish our small tank cascades system - an ideal solution for climate woes. Thanks to the untiring efforts of a knowledgeable few, the single-tank approach has being somewhat shelved and the cascade approach is being adopted. It should move further from cascade to ‘mini watersheds’ surrounding those cascades. The cascade system would not function properly unless the surrounding catchments, including other elements of the system, are functioning and protected. However, what we often see are haphazard settlements and misuse. Smaller water bodies in the catchments are meant for sediment trapping, groundwater recharging, and for the use of animals. Those are part of the same system of tank cascades and not appendages. Increasingly, those smaller waterholes are converted to irrigation tanks under the guise of ‘participatory rehabilitation’ through the projects.

In the water catchment areas of the central highlands, we need to stop soil erosion on slopes and increase the moisture retention capacities. Otherwise, our rivers will run dry, anicut schemes will have to be abandoned, and all irrigation systems located in the Dry Zone will suffer from water shortages. As a result, hydropower generation will be in jeopardy. There will be more land and mudslides, denuded hills, dried waterfalls, devastated tea and vegetable gardens, and rampant poverty. In the lower lands, most of the suitable areas for water storage are already occupied and it is not feasible to allocate land for reservoirs which only fill up once in 10-15 years. Also, the existing reservoirs are heavily polluted, silted, and have poor storage capacities.

Heavy rains during short periods may not help recharge groundwater. Pollution and over-abstraction could hamper the available limited quantities of groundwater, particularly in coastal areas. Coastal zone freshwater could become salinized either by over-extraction or sea level rises which will in turn  threaten the  livelihoods of millions of people.

Water is not the only area which affects climate change. That is why climate change has to be mainstreamed into programmes and policies.

Dr. Herath Manthrithilake serves as the Head of the Sri Lanka Development Initiative of the International Water Management Institute (IWMI), which is one node of a research network called Consultative Group of International Agricultural Research (CGIAR). He has vast experience in civil engineering, water resources management, watershed management, rural infrastructure development, environment conservation, teaching at postgraduate institutes and on project management.